Forwarding data in a data communications network

Abstract

An apparatus is described for forwarding data in a data communications network having as components nodes and links therebetween in which nodes obtain a reachability metric between a neighbor node and one or more other nodes in the network and in which a repair path is created between an instigating repair node and a receiving repair node around a failure component therebetween. A propagatable repair address for the receiving repair node is reachable by the repair path notvia the failure component. The apparatus is arranged to treat propagatability of the repair address differently via the failure component than via other components.

1. An apparatus for forwarding data in a data communications network, having as components nodes and links therebetween, the apparatus comprising:
 one or more processors; and 
 a machine-readable storage medium storing one or more sequences of instructions, which when executed by the one or more processors, cause the one or more processors to perform:
 while a failure component is still operational:
 obtaining a reachability metric between a neighbor node and one or more other nodes in the data communications network; 
 creating a repair path between an instigating repair node and a receiving repair node around the failure component therebetween and a propagatable repair address for the receiving repair node is reachable by a repair path notvia the failure component; 
 treating propagatability of the repair address differently via the failure component than via other components; 
 
 wherein the repair path notvia the failure component is pre-computed while the failure component is still operational and does not include the failure component; 
 wherein the propagatable repair address is propagated while the failure component is still operational; and 
 wherein the propagatable repair address is propagated via the repair path notvia the failure component. 
 
 
   
   
     2. An apparatus as claimed in  claim 1  wherein the receiving repair node is arranged to treat propagatability of the repair address differently by only propagating the repair address via components other than the failure component. 
   
   
     3. An apparatus as claimed in  claim 1  wherein the receiving repair node is arranged to treat propagatability of the repair address differently by propagating the repair address via the failure component with a differentiating characteristic. 
   
   
     4. An apparatus as claimed in  claim 1  wherein the receiving repair node is arranged to treat propagatability of the repair address differently by propagating the repair address via the failure component with a differentiating characteristic, wherein the differentiating characteristic comprises a cost characteristic or an address class. 
   
   
     5. An apparatus as claimed in  claim 1  the receiving repair node is arranged to treat propagatability of the repair address differently by only propagating the repair address via components other than the failure component, wherein the receiving repair node is arranged to signal to the instigating repair node to identify the repair address as an address for repair of failure of the failure component. 
   
   
     6. An apparatus as claimed in  claim 1  wherein the instigating repair node is arranged to treat propagatability of the repair address differently by suppressing propagation of the repair address or propagating the repair address with a differentiating characteristic. 
   
   
     7. An apparatus as claimed in  claim 1  wherein the instigating repair node is arranged to treat propagatability of the repair address differently by suppressing propagation of the repair address or propagating the repair address with a differentiating characteristic, wherein the instigating repair node is arranged to identify the repair address as a repair address for a repair path around a failure component. 
   
   
     8. An apparatus as claimed in  claim 1  wherein the repair path node is arranged to update forwarding information for the repair address computed according to a distance vector protocol. 
   
   
     9. An apparatus as claimed in  claim 1  wherein the repair path node is arranged to update forwarding information for the repair address computed according to a distance vector protocol, wherein the repair path node is arranged to forward non-repair address traffic via a route computed by a distance vector protocol. 
   
   
     10. An apparatus as claimed in  claim 1  in which the receiving repair node is arranged to propagate the repair address to each neighbor excluding a failure component node. 
   
   
     11. An apparatus as claimed in  claim 1  in which the reachability metric comprises a distance vector metric. 
   
   
     12. An apparatus as claimed in  claim 1  wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to further perform:
 determining if a loop free alternate (LFA) is available, and in response thereto, forwarding via the LFA rather than the notvia address. 
 
   
   
     13. A method of forwarding data in a data communications network having as components nodes and links therebetween, comprising:
 while a failure component is still operational:
 receiving a reachability metric between a neighbor node and one or more other nodes in the data communications network; 
 creating a repair path notvia the failure component, the repair path being between an instigating repair node and a receiving repair node around the failure component therebetween; 
 receiving a propagatable repair address for the receiving repair node reachable by the repair path notvia the failure component; and 
 propagating the repair address notvia the failure component. 
 
 
   
   
     14. A method as claimed in  claim 13  further comprising a repair node treating propagatability of the repair address differently by only propagating the repair address via components other than the failure component. 
   
   
     15. A method as claimed in  claim 13  wherein the receiving repair node treats propagatability of the repair address differently by propagating the repair address via the failure component with a differentiating characteristic. 
   
   
     16. A method as claimed in  claim 13  wherein the receiving repair node treats propagatability of the repair address differently by propagating the repair address via the failure component with a differentiating characteristic, wherein the differentiating characteristic comprises a cost characteristic or an address class. 
   
   
     17. A method as claimed in  claim 13  wherein the receiving repair node treats propagatability of a repair address differently by only propagating the repair address via components other than the failure component, wherein the receiving repair node is arranged to signal to the repair instigating node to identify the repair address as an address for repair of failure of the failure component. 
   
   
     18. An apparatus comprising:
 one or more processors; and 
 a network interface communicatively coupled to the one or more processors and configured to communicate one or more packet flows among the one or more processors in a network; 
 while a failure component is still operational:
 means for receiving a reachability metric between a neighbor node and one or more other nodes in the network; 
 means for creating a repair path not via the failure component, the repair path being between an instigating repair node and a receiving repair node around the failure component therebetween; 
 means for receiving a propagatable repair address for the receiving repair node is reachable by the repair path notvia the failure component; and 
 means for propagating the repair address notvia the failure component. 
 
 
   
   
     19. An apparatus as claimed in  claim 18  wherein the receiving repair node comprises means to treat propagatability of the repair address differently by only propagating the repair address via components other than the failure component. 
   
   
     20. An apparatus as claimed in  claim 18  wherein the receiving repair node comprises means to treat propagatability of the repair address differently by propagating the repair address via the failure component with a differentiating characteristic. 
   
   
     21. An apparatus as claimed in  claim 18  wherein the receiving repair node comprises means to treat propagatability of the repair address differently by propagating the repair address via the failure component with a differentiating characteristic, wherein the differentiating characteristic comprises a cost characteristic or an address class. 
   
   
     22. An apparatus as claimed in  claim 18  wherein the receiving repair node comprises means to treat propagatability of the repair address differently by only propagating the repair address via components other than the failure component, wherein the receiving repair node is arranged to signal to the repair instigating node to identify the repair address as an address for repair of failure of the failure component.